NONLINEAR CONTROL OF BIOREACTORS WITH INPUT MULTIPLICITIES

Control of bioreactors exhibiting two input multiplicities, i.e., stea dy-state gains having opposite sign, is theoretically analyzed. The no nlinear system is represented by a unity gain linear system cascaded w ith a nonlinear gain. A conventional PI controller designed for the li near portion of the system followed by the solution of the nonlinear g ain equation gives a nonlinear controller. The performance of the nonl inear controller is compared with that of the linear PI controller des igned for the overall linear system. The nonlinear PI controller perfo rmance is superior to that of the linear PI controller.